The present disclosure relates to contactless power transmission devices used for charging, for example, electric propulsion vehicles, such as electric vehicles, plug-in hybrid vehicles, etc.
FIG. 8 is a diagram schematically showing a configuration of a conventional contactless power transmission device 6 (see, for example, Japanese Unexamined Patent Publication No. 2008-87733). In FIG. 8, a contactless power feeder (primary device) F which is provided on the ground and is connected to the power source board of a power source 9 is positioned during power feed, facing a power receiver (secondary device) G which is mounted in an electric propulsion vehicle, without physical contact therebetween, i.e., with an air gap (empty space) being interposed therebetween. In such an arrangement, when an alternating current is applied to a primary coil 7 included in the power feeder F to generate magnetic flux, electromotive force is induced in a secondary coil 8 included in the power receiver G, whereby power is contactlessly transmitted from the primary coil 7 to the secondary coil 8.
The power receiver G is connected to, for example, an in-vehicle battery 10, which is charged with the above transmitted power. An in-vehicle motor 11 is driven by the power accumulated in the in-vehicle battery 10. Note that, during the contactless power feed process, necessary information is exchanged between the power feeder F and the power receiver G by, for example, a wireless communication device 12.
FIGS. 9A and 9B are diagrams schematically showing an internal structure of the power feeder F and the power receiver G. In particular, FIG. 9A is a diagram schematically showing an internal structure of the power feeder F as viewed from the top or the power receiver G as viewed from the bottom. FIG. 9B is a diagram schematically showing an internal structure of the power feeder F and the power receiver G as viewed from the side.
In FIGS. 9A and 9B, the power feeder F includes the primary coil 7, a primary magnetic core 13, a back plate 15, a cover 16, etc. The power receiver G includes the secondary coil 8, a secondary magnetic core 14, a back plate 15, a cover 16, etc., and briefly, has a structure symmetric to that of the power feeder F. The surfaces of the primary coil 7 and the primary magnetic core 13, and the surfaces of the secondary coil 8 and the secondary magnetic core 14, are each covered and fixed with a molded resin 17 containing a foam material 18.
Specifically, in the power feeder F and the power receiver G, a space between the back plate 15 and the cover 16 is filled with the molded resin 17, and therefore, the surfaces of the primary and secondary coils 7 and 8 and the surfaces of the primary and secondary magnetic cores 13 and 14 are covered and fixed. The molded resin 17 is formed of, for example, silicone resin. Because the internal space is thus filled with the solid resin, the primary and secondary coils 7 and 8 can be positioned and fixed, and therefore, their mechanical intensity can be ensured, and at the same time, their heat can be dissipated. Specifically, the passage of an excitation current through the primary and secondary coils 7 and 8 releases Joule heat, which is then dissipated by heat conduction through the molded resin 17, and therefore, the primary and secondary coils 7 and 8 are cooled.